Fuel injection apparatus

ABSTRACT

Apparatus for the injection of fuel into the intake manifold of an internal combustion engine is described. The apparatus includes an air-assist nozzle that has a chamber formed in it that includes an orifice for the discharge of air-atomized fuel. A fuel injector has a fuel discharge port positioned within the chamber of the air-assist nozzle. The air-assist nozzle has an air inlet to the chamber, and air which enters the chamber through the inlet mixes with the fuel discharged from the fuel injector producing an air-fuel atomized mixture which is discharged from the orifice of the air-assist nozzle.

United States Patent 1191 Boltz et al. Jan. 1, 1974 [54] FUEL INJECTIONAPPARATUS 1,898,763 2/1933 Cowardin et: al. 239/403 x [75] Inventors:Ronald R. Boltz, Oak Park; William J a Dearbom Heights, both of2,893,365 7/1959 Haefner 123/139 AW Mich.

[73] Assignee: Ford Motor Company, Dearborn, Primary Examiner-M HensonWood, 113

Mich Assistant Examiner-John J. Love Attorney-Keith L. Zerschling et al.[22] Filed: Apr. 17, 1972 [21] Appl. No.: 244,441 [57] ABSTRACTApparatus for the injection of fuel into the intake 52] us. c1 239/405,239/4345, 239/470, manifold of an internal Combustion F 2 is 239/533,239/585, 123/139 AW scribed. The apparatus includes: an alr-assistnozzle 51 rm. (:1 BOSb 1/34 that has a chamber formed in it thatincludes an 58 Field of Search 239/403, 405, 468, fice for the dischargeof air'atomiled fuel- A fuel 239/469, 470, 585, 533, 399, 401, 434.5;jector has a fuel discharge port positioned within the 123/139 w chamberof the air-assist nozzle. The air-assist nozzle has an air inlet to thechamber, and air which enters [56] References Cited the chamber throughthe inlet mixes with the fuel dis- UNITED STATES PATENTS charged fromthe fuel injector producing an air-fuel atomized mixture which isdischarged from the orifice 1,495,731 5/1924 Gerdes et al 239/405 of theair assist nozzle 2,755,134 7/1956 Eck et a] 239/403 X 1,457,849 6/1923Morse 239/405 1 Claim, 3 Drawing Figures FUEL INJECTION APPARATUSBACKGROUND OF THE INVENTION This invention relates to apparatus forinjecting fuel into the intake manifold of an internal combustion engineand, more particularly, to fuel injection apparatus including anair-assist nozzle having a swirl chamber within it which, in combinationwith a fuel injector that may be of conventional design, produces ahighly atomized mixture of air and fuel that is discharged into theintake manifold of an internal combustion engine. The invention isapplicable to both electronic and mechanical fuel injection systems forinternal combustion engines.

Fuel injection systems for internal combustion engines have undergonemuch development over the years. Fuel injection systems for such enginesfall into two broad classes, that is, those in which fuel is injecteddirectly into the engines combustion chambers and those in which fuel isinjected into an intake passage preceding the combustion chambers. Theteachings of the present invention are particularly applicable to fuelinjected engines in the latter classification, but are believed to beapplicable to the former class of fuel injected engines also.

One of the greatest problems encountered in the application of fuelinjection systems to internal combus tion engines is in finding meansfor achieving adequate atomization of the fuel injected into the engine.If the fuel is inadequately atomized in the combustion air, incompletecombustion may result and it may be necessary to supply a greaterquantity of fuel to the engine than would otherwise be required were theatomization of the air and fuel adequate. Where the amount of fuelinjected into an engine exceeds the amount which can be consumed in theengine combustion process, the engine necessarily must discharge theexcess fuel to the atmosphere as a part of its exhaust emission. Also,inadequate atomization of the fuel can have a detrimental effect on theperformance of an engine, particularly when the engine is cold and fuelinjected into it is likely to impinge on engine parts and condense.

SUMMARY OF THE INVENTION The fuel injection apparatus of the inventioncomprises an air-assist nozzle having a chamber within it. The chamberhas an air inlet passage in communication with the chamber. The chamberin the air-assist nozzle has a cylindrically shaped first portion and acoaxial frusto-conically shaped second portion. The air inlet passage tothe chamber approaches the cylindrically shaped portion thereof from asubstantially tangential direction. The air-assist nozzle also has anorifice for the discharge of air-atomized fuel. The orifice communicateswith the chamber at the smaller diameter end of the frusto-conicallyshaped second chamber portion. Means, such as a commercially availablefuel injector, is used with the air-assist nozzle for the discharge offuel into its chamber. The fuel discharge means includes a fueldischarge nozzle that is positioned within the chamber of the air-assistnozzle. Preferably, this fuel discharge nozzle has a discharge portpositioned on the axis of the air-assist nozzle chamber and thedischarge port is axially spaced from the orifice in the airassistnozzle.

Preferably, the fuel injection apparatus of the invention is-used toinject fuel into an air intake passage preceding the combustion chamberof a reciprocating or rotating internal combustion engine. In suchengines, a throttle valve is used to control the air entering the airintake passage. In an engineof this type, the air pressure in the airintake passage is less than atmospheric pressure during engineoperation, but fluctuates from a very low absolute pressure to almostatmospheric pressure depending on engine speed, throttle angle position,exhaust system back pressure and the like. The air-assist nozzledescribed above, when used in conjunction with means for dischargingfuel intoits chamber, effectively isolates the fuel discharge means fromthe fluctuations in air intake passage pressure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of fuelinjection apparatus constructed in accordance with the invention andpositioned in a portion of an intake manifold of an internal combustionengine;

FIG. 2 is an enlarged sectional view ofthe fuel injection apparatus ofFIG. 1, the location at which the sectional view of FIG. 2 is takenbeing indicated by the line 2-2 in FIG. 3; and

FIG. 3 is an enlarged sectional view of the fuel injection apparatus,the section being taken along the line 3-3 indicated in FIG. 2.

DETAILED DESCRIPTION With reference now to the drawings, wherein likenumerals refer to like parts in the several views, there is shown fuelinjection apparatus constructed in accordance with the invention.

FIG. 1 is a sectional view ofa portion of the cylinder head and airintake manifold of a reciprocating internal combustion engine whichutilizes fuel injection in its operation. The cylinder head 10 is ofconventional construction and includes an intake poppet valve 12 which,when opened, permits a mixture of air and fuel to be drawn through theintakeport 1-4 into a combustion chamber (not shown) below the cylinderhead 10. Combustion air is supplied to the cylinder head 10 through anair passage 16 in an air intake manifold 18 that is attached to thecylinder head 10.

Fuel injection apparatus, generally designated by the numeral 20, ismounted in an opening 22 in the intake manifold 18 and is positionedtherein such that a mixture of atomized air and fuel 24, when dischargedfrom the fuel injection apparatus 20 is directed toward the intake valve12 and intake port 14. The fuel injection apparatus 20 comprises anair-asist nozzle 26 having a chamber 28 within it, and means fordischarging fuel into the chamber 28 in the form of an electromagneticfuel injector 30. An air inlet 29 communicates with the chamber 28 ofthe air-assist nozzle. The air-assist nozzle 26 and fuel injector 30 areheld in position in the intake manifold 18 with a plate 32, which isfitted into a groove 34 in the fuel injector, and bolts 36 and 38threaded into the intake manifold.

FIGS. 2 and 3 are enlarged sectional views of the fuel injectionapparatus 20. It may be seen that the air-assist nozzle 26 is comprisedof a nozzle body 40, a nozzle orifice insert 42, and an annular thermalinsulator 44, which may be made from a material such as micarta. Thenozzle body 40 has a cylindrically shaped opening 46 which is threadedat one end to receive the nozzle orifice insert 42. The orifice insert42 has a frustoconically shaped portion 48 which, when positioned in thenozzle body 40 as shown in FIG. 2, is coaxial with the cylindricalopening 46 in the nozzle body and which, with the nozzle body, forms thechamber 28. Thus, the chamber 28 has a cylindrical-shaped first portionand a coaxial frusto-conically shaped second portion. An orifice 50 inthe nozzle orifice insert 42 communicates with the chamber 28 at thesmaller diameter end of the frusto-conically shaped second chamberportion. The air-assist nozzle 26 may be formed from a single piece, ifdesired. Also specific dimensions of the air-assist nozzle 26 areimportant and are affected by the design'of the fuel injector 30.

The air inlet 29 preferably communicates with the cylindricallyshaped-first portion of the chamber 28 and approaches this cylindricallyshaped. portion of the chamber from a direction that is tangential withrespect to the cylindrical opening 46,- as may best be seen in FIG. 3.

Where the internal combustion engine is controlled by means. of anairthrottle.(n ot shown) positioned in the intake manifold 18, the airpressure within the flow passage 16 of the manifold fluctuates from verylow absolute pressuresat engine idling conditions to absolutepressures'near atmospheric pressure during wide open throttle operationof the engine. Intake manifold pressure also fluctuates with time (crankengine angle) at a fixed average manifold pressure. In the absence ofthe air-assist nozzle this creates a varying differential pressureacrossthe discharge nozzle of the fuel injector 30. It is an object ofthe invention to isolate the fuel injector 30 from the intake manifoldpressure fluctuations. For this reason, the air inlet 29 to the chamber28 of the air-assist nozzle preferably is connected to a source of airwhich is at or near atmospheric pressure. The effect of this on theoperation of the fuel injection apparatus 20 is described hereinafter.

The fuel injector 30 is of a design presently in commercial use. Itcomprises an injector body 52 that is positioned in the annularinsulator 44 of the air-assist nozzle 26, which thermally isolates itfrom the air-assist nozzle. An air space 54 between the insulator 44 andthe nozzle body 40 aids in this thermal isolation.

The injector body 52 has a fuel discharge nozzle 56 positioned withinit. The nozzle 56 has a fuel discharge port 58, which includes a valveseat 60, that is positioned within the cylindrically shaped firstportion of the chamber 28 and preferably is located as shown on thecommon axis 62 of the cylindrically shaped and frusto-conically shapedportions'of the chamber 28.

Also, it is preferable that the discharge port 58 of the fuel nozzle 56be axially spaced from the orifice 50 and that it be positionedintermediate the air inlet 29 and the orifice 50, as may best be seen inFIG. 2.

The fuel injector 30 is electromagnetically operated by a coil 64 which,when energized, moves an armature 66 against the force of a spring 68.Fuel enters the injector 30 through an inlet 70 and travels through apassage 72 and is then deposited in a chamber 74 in the fuel nozzle 56.

' As the air is drawn toward the orifice 50 in the nozzle insert 42',its angular velocity increases because of the frusto-conically shapedportion of the chamber 28. This swirling air mixes with the fueldischarged in the chamber 28 from the fuel discharge port 58 and resultsin a finely atomized mixture of air and fuelbeing discharged through theorifice 50 into the intake manifold passage 16.

It should be noted that the discharge port 58 of the fuel injector 30 isisolated from the fluctuating subatmospheric pressure in the intakepassage 16 by the atmospheric air which enters the swirl chamber 28 ofthe air-assist nozzle and that a variable pressure drop will occuracross the orifice 50 of the nozzle insert. In practice, very excellentair and fuel atomization has been obtained with an air-assist nozzle inwhich the orifice 50 has a length to diameter ratio of 1.0 and in whichthe frusto-conically shaped portion of the chamber 28 forms angle of 45with respect to the axis 62. 1

Based upon the foregoing description of the invention, what is claimedand desired tobe protected by Letters Patent is:

L'Apparatus for the injection of fuel into the intake manifold of aninternal combustion engine, said apparatus comprising: an air-assistnozzle positioned in said engine intake manifold, said air-assist nozzlehaving a chamber formed in it, said chamber having a cylindricallyshaped first portion and a coaxial frusto-conically tion from atangential direction; and means for dis- I charging fuel into saidair-assist nozzle chamber, said fuel discharge means having a dischargeport located within said chamber, said discharge port being positionedon the axis of said chamber in said air-assist nozzle and being locatedwithin said cylindrically shaped first portion of said air-assist nozzlechamber, said discharge port being axially spaced from said air-assistnozzle orifice and being positioned intermediate said air-assist nozzleair inlet passage and said air-assist nozzle discharge orifice.

1. Apparatus for the injection of fuel into the intake manifold of aninternal combustion engine, said apparatus comprising: an air-assistnozzle positioned in said engine intake manifold, said air-assist nozzlehaving a chamber formed in it, said chamber having a cylindricallyshaped first portion and a coaxial frustoconically shaped secondportion, said air-assist nozzle having an orifice for the discharge ofair-atomized fuel from said chamber into said engine intake manifold,said orifice communicating with said chamber at the smaller diameter endof said frusto-conically shaped second chamber portion, said air-assistnozzle having an air inlet passage in communication with saidcylindrically shaped first chamber portion, said air inlet passageapproaching said cylindrically shaped first chamber portion from atangential direction; and means for discharging fuel into saidair-assist nozzle chamber, said fuel discharge means having a dischargeport located within said chamber, said discharge port being positionedon the axis of said chamber in said air-assist nozzle and being locatedwithin said cylindrically shaped first portion of said air-assist nozzlechamber, said discharge port being axially spaced from said air-assistnozzle orifice and being positioned intermediate said air-assist nozzleair inlet passage and said air-assist nozzle discharge orifice.